1. Field of the Invention
This invention relates to roll casting of a molten metal. More particularly, the invention relates to an improved roll caster feed tip and method.
2. Description of the Prior Art
The casting of a molten metal by continuous rolling is well known to those skilled in the art. With roll casters such as that disclosed in U.S. Pat. Nos. 2,790,216 and 4,054,173, molten metal such as aluminum, tin or copper is efficiently rolled into plate, strip or sheet product. The typical roll caster includes a pair of water-cooled rolls that rotate in opposite directions and have a slight gap or space therebetween. When molten metal is fed from a feed tip or nozzle into the roll gap, it rapidly solidifies between or near the rolls to form sheet product. The width of said sheet product is ultimately limited by the dimensions of the roll gap. Casting widths are further controlled, however, by the width of the feed tip outlet. For example, a feed tip having an outlet width of 1 meter (39 inches) casts only sheet product of about the same width, even when positioned adjacent wider roll gaps.
In many instances, it is desirable to produce sheet product of various widths from the same casting of molten metal or metal alloy. Until this invention, however, it was not possible to provide a feed tip having an adjustable outlet width. Conventional roll caster feed tips are made from a plurality of segments joined together and sealed at both ends to produce a particular width of sheet product. In U.S. Pat. Nos. 4,232,804 and 4,303,181, for example, each feed tip segment is about 15 cm (5.9 inches) wide. A plurality of said segments are bolted together to produce sheet product having a particular width between 1.5-2.0 meters (59-79 inches). After a first width of sheet product has been cast, presently known art requires stopping the flow of molten metal to the caster, substituting one feed tip for another and restarting the casting operation. Such casting interruptions are costly in terms of the production time lost and man-hours spent assembling and installing feed tips having various outlet widths. Repeated interruptions also increase the risk of damage to roll casting equipment from undetected deposits of frozen metal.
With respect to the continuous mold casting of metal strands, it is further known to vary the cross-sectional area of the strands by changing the angle of sidewall inclination. Exemplary of such mold variations are those disclosed in U.S. Pat. Nos. 4,134,441 and 4,270,593. There is no teaching or suggestion in either reference to similarly modify a roll caster feed tip. Should the modification be attempted, however, molten metal will tend to leak from movable feed tip sides.